I’ve seen quite a few people on twitter asking approximately the same question:
Has anyone encountered problems with video not working when testing .mobi files in the Kindle apps? #eprdctn
— Charlie Stephenson (@crjs20) May 12, 2014
The best answer from the community seems to be that you CAN’T test KF8 video through side-loading (I can confirm this to be true) but you CAN test it once the book has been put up for sale on Amazon (I can’t test this—my publisher submits through KDP).
Anyone want to confirm this? An Amazon response would be great, but personal experiences are welcome as well.